// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/base/dragdrop/drag_utils.h"

#include "base/files/file_util.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/strings/utf_string_conversions.h"
#include "build/build_config.h"
#include "ui/base/dragdrop/os_exchange_data.h"
#include "ui/gfx/canvas.h"
#include "ui/gfx/font_list.h"
#include "ui/gfx/geometry/point.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/size.h"
#include "ui/gfx/image/canvas_image_source.h"
#include "url/gurl.h"

namespace drag_utils {

namespace {

    // Maximum width of the link drag image in pixels.
    static const int kLinkDragImageVPadding = 3;

    // File dragging pixel measurements
    static const int kFileDragImageMaxWidth = 200;
    static const SkColor kFileDragImageTextColor = SK_ColorBLACK;

    class FileDragImageSource : public gfx::CanvasImageSource {
    public:
        FileDragImageSource(const base::FilePath& file_name,
            const gfx::ImageSkia& icon)
            : CanvasImageSource(CalculateSize(icon), false)
            , file_name_(file_name)
            , icon_(icon)
        {
        }

        ~FileDragImageSource() override { }

        // Overridden from gfx::CanvasImageSource.
        void Draw(gfx::Canvas* canvas) override
        {
            if (!icon_.isNull()) {
                // Paint the icon.
                canvas->DrawImageInt(icon_, (size().width() - icon_.width()) / 2, 0);
            }

            base::string16 name = file_name_.BaseName().LossyDisplayName();
            const int flags = gfx::Canvas::TEXT_ALIGN_CENTER;
            const gfx::FontList font_list;
#if defined(OS_WIN)
            // Paint the file name. We inset it one pixel to allow room for the halo.
            const gfx::Rect rect(1, icon_.height() + kLinkDragImageVPadding + 1,
                size().width() - 2, font_list.GetHeight());
            canvas->DrawStringRectWithHalo(name, font_list, kFileDragImageTextColor,
                SK_ColorWHITE, rect, flags);
#else
            // NO_SUBPIXEL_RENDERING is required when drawing to a non-opaque canvas.
            const gfx::Rect rect(0, icon_.height() + kLinkDragImageVPadding,
                size().width(), font_list.GetHeight());
            canvas->DrawStringRectWithFlags(name, font_list, kFileDragImageTextColor,
                rect,
                flags | gfx::Canvas::NO_SUBPIXEL_RENDERING);
#endif
        }

    private:
        gfx::Size CalculateSize(const gfx::ImageSkia& icon) const
        {
            const int width = kFileDragImageMaxWidth;
            // Add +2 here to allow room for the halo.
            const int height = gfx::FontList().GetHeight() + icon.height() + kLinkDragImageVPadding + 2;
            return gfx::Size(width, height);
        }

        const base::FilePath file_name_;
        const gfx::ImageSkia icon_;

        DISALLOW_COPY_AND_ASSIGN(FileDragImageSource);
    };

} // namespace

void CreateDragImageForFile(const base::FilePath& file_name,
    const gfx::ImageSkia& icon,
    ui::OSExchangeData* data_object)
{
    DCHECK(data_object);
    gfx::CanvasImageSource* source = new FileDragImageSource(file_name, icon);
    gfx::Size size = source->size();
    // ImageSkia takes ownership of |source|.
    gfx::ImageSkia image = gfx::ImageSkia(source, size);

    gfx::Vector2d cursor_offset(size.width() / 2, kLinkDragImageVPadding);
    SetDragImageOnDataObject(image, cursor_offset, data_object);
}

void SetDragImageOnDataObject(const gfx::Canvas& canvas,
    const gfx::Vector2d& cursor_offset,
    ui::OSExchangeData* data_object)
{
    gfx::ImageSkia image = gfx::ImageSkia(canvas.ExtractImageRep());
    SetDragImageOnDataObject(image, cursor_offset, data_object);
}

} // namespace drag_utils
